Putty on joints to make skin flush

[stona]

After reading this I have a picture in my mind of the wing looking as though it were moulded in one piece, like fibreglass. Repairs must have been tricky what with not being able to see where the rivets were in order to drill them out, and then having to go through the repainting process once the damaged area had been replaced. I expect the area around the damage had to be stripped of paint just to find the rivets.

In the RAF this sort of finishing only applied to aircraft deemed high speed. It was not applied to heavy bombers, flying boats, trainers and so on.
In the film I posted an example is made of how to repair a scuff at the wing root, even that is not as straight forward as one might imagine!
Crews were expected to look after the finish of the aircraft in their charge.

Yet another reason why my models don't look like patchwork quilts

Steve

 

[swampyankee]

Boeing's web site (Painting versus Polishing of Airplane Exterior Surfaces) has some information on the weights of paint for modern aircraft. Interestingly, Boeing claims that the operating costs of unpainted (polished metal) aircraft are higher than painted aircraft.

I've read that the paint on a completely painted 747 weighs about 1100 lb. If I remember, a 747 has about 5500 square feet of wing area and probably a total wetted area around 25,000 square feet, so modern paint weighs something like 0.04 lb/ft^2.

 

[tyrodtom]

A 747 would be painted with a polyurethane enamel, like Duponts Imron.
A modern paint developed for the aviation industry in the late 60's-early 70's, now also used heavily in the trucking industry too.
It has much less film thickness required for coverage than the old enamels or lacquers that would have been used on WW2 aircraft.

I've painted Imron myself, on trucks and aircraft parts. It's one of those paints that will send you to a hospital quick if you don't use the proper breathing protection.

 

[Maxrobot1]

So it seems that the assembly lines at North American had to allow for the steps of hand finishing the wing assemblies. Also any model of a P-51 that features visible rivets on the upper or lower wings would be incorrect! Any panel lines except for the gun bays would be hidden.
A trend has developed in the model building community where the modeler darkly shades the panel lines as a form of weathering. I guess this would not apply to P-51s!

 

[stona]

A trend has developed in the model building community where the modeler darkly shades the panel lines as a form of weathering. I guess this would not apply to P-51s!

Or other high speed aircraft!

Steve

 

[swampyankee]

I've painted Imron myself, on trucks and aircraft parts. It's one of those paints that will send you to a hospital quick if you don't use the proper breathing protection.

My bike was repainted with Imron (I also had some bits added, a new head tube bearing, some braze-ons, and the rear dropouts modified so I could get a new derailleur). It's stood up very well. On the hospitalization bit: the man who has done some body work on my cars refuses to use Imron, mostly because he views it as too risky.

 

[nuuumannn]

I expect the area around the damage had to be stripped of paint just to find the rivets.

You grind the paint off with a fine abrasive wheel as you roughly know where the rivest are going to be, having looked at the wing station numbers in the manual to find the panel joints. Once the layers of paint are removed, you drill out the rivet heads.

Yep; modern aircraft paints and the solvents associated are toxic; I know guys who have worked as aircraft painters with repiratory problems and as a result of exposure to carcinogens, particularly MEK (Methyl Ethyl Ketone, used variously as a solvent cleaner and useful stripper of material from metal surfaces) have high amounts of cancer cells in their bodies. When I did my apprenticeship I used to volunteer to do paint strips - which, not only is bad for your insides, will burn your skin off as well, although most companies use far milder, but no less effective paint stripper than the old Ardrox stuff we used to use, but if you got any on your skin, you'd have a scar for a couple of weeks or so. Full body suits, respirators and face covers are essential. If any paint stripper fell on your face mask, you had to go replace it, otherwise it'd fuzz the plastic and you couldn't see. I was doing the underside of a P-3 once and my mask was knocked off and I got a glob of stripper on my face. Burns a bit. We used to wash ourselves down with MEK before taking a shower with all our kit on to get the solvents off.

 

[Airframes]

I used to use MEK in the printing industry. It's used for cleaning printing plates, as well as other applications (it's also used as a liquid cement for plastics).
Put some on a wad of cotton wool, let it evaporate slightly, and it makes a contact explosive! Great fun when thrown against a wall or hard surface!
(Don't try this at home kids!!).
Dangerous stuff to handle, and not good for health.

 

[nuuumannn]

Dangerous stuff to handle, and not good for health.

Yep, sure is; it's a known carcinogen. There are aviation maintenance firms that outright refuse to use it anymore because of the dangers to health it poses, but many still do. As a solvent it takes some beating. When I first arrived back in New Zealand I bought a 100 year old villa and I came across a wood putty for restoring wooden window frames that contained MEK in it in a store, but when I ran out and went back for more, it had been removed from use and the store no longer stocked it. Probably because of the hazard it poses.

 

[Milosh]

When at Sperry (mid 70s) we used MEK to clean the bearings used in gyros. Put the bearing in a dish filled with MEK and spin the outer race with our bare finger while holding the inner race with the fingers of other hand.

Wish I knew about that Airframes.

 

[Aozora]

My granddad had a used car lot in the 1970s; MEK was used in a paste that was used to cut and polish the cars, and it looks like its still being used
Chauffeur's Choice car care products
imagine all that product being stacked in a badly ventilated garage...

and MEK is still available...

Methyl Ethyl Ketone (MEK)

 

[swampyankee]

Off the track of paints and toxic solvents, I remember reading that the Soviets would put thick layers of wax on their planes to give them a good, but short-lived, smooth surface finish.

When I worked at Lycoming, we (more specifically, the test technicians) would use bowling alley wax to polish and smooth the bellmouths we used for engine testing.

 

[pattle]

My granddad had a used car lot in the 1970s; MEK was used in a paste that was used to cut and polish the cars, and it looks like its still being used
Chauffeur's Choice car care products
imagine all that product being stacked in a badly ventilated garage...

and MEK is still available...

Bloody hell I didn't realise that MEK was methyl ethyl ketone, in the eighties I used that stuff for cleaning compressor vanes and I even put the odd cheeky drop in my zippo from time to time as well, it give a very nice tall blue flame which was good for lighting up outdoors in bad weather.

 

[stona]

MEK is not a listed carcinogen. It is a mutagen which is not the same.
It is toxic and can be absorbed through the skin. There will be various material safety data sheets (MSDS) available with a quick google. These will, or should, highlight possible detrimental effects on health and the environment in a fairly bleak way. They rightly tend to err on the side of caution and should set low exposure limits and give advice on personal protection equipment (PPE) to be worn.
Years ago we used it in an open lab (not a fume cupboard or similar) wearing eye protection and gloves, no respirator. Given the limited exposure I would get making a model I would happily fill my cement bottle with MEK.
If it was as dangerous as some of you are supposing it would not be available in over the counter type products.
Cheers
Steve (ex -chemist, and organic at that!)

 

[bobbysocks]

with your acrylic enamal paint when used as with a catalyst additive and the poly-urethanes...TEK base, etc. it isnt so much that they are carcinogens...which they very well may be. but the problem was back in the old days with acrylic lacquer, synthol enamel and the early acrylic enamels ( non-catalysed) painters rarely wore masks. some would wrap a bandana bandit style...others would maybe wear a cheapo dust mask, but most i knew didnt wear anything. i grew up mixing and selling automotive paint in the family business. once, what sherwin williams called catyl-ad was introduced as a hardner, a good grade canister style paint mask was an absolute must....with the P/Us and later stuff full coverage suits and closed circuit air systems were recommended. once the overspray got on your lungs it was there FOREVER. a large majority of the shops just painted in a garage and practically no one had ventilated booths. so once they started spraying the fogof paint was so thick you could cut it. several painters who refused to change their ways were taken down by the stuff after only a paint job or two. i mean permanently disabled with a horrible case of COPD...they were as bad or worse than the minors who had black lung. that stuff is wicked.

 

[fastmongrel]

I dont know much about paints but I do remember an old body shop guy telling me that when 2 pack paints came in spray painters went down like flies with liver (might have been kidney) problems. Apparently there were warnings on the tins but who reads a warning label, it was only when there were deaths that spray painters started using air hoods and extractors.

 

[stona]

Liver sounds right, but I was a chemist, not a doctor
Either way it's a sad story.
Steve

 

[MiTasol]

[/QUOTE]

MEK is not a listed carcinogen. It is a mutagen which is not the same.
It is toxic and can be absorbed through the skin. There will be various material safety data sheets (MSDS) available with a quick google. These will, or should, highlight possible detrimental effects on health and the environment in a fairly bleak way. They rightly tend to err on the side of caution and should set low exposure limits and give advice on personal protection equipment (PPE) to be worn.
Years ago we used it in an open lab (not a fume cupboard or similar) wearing eye protection and gloves, no respirator. Given the limited exposure I would get making a model I would happily fill my cement bottle with MEK.
If it was as dangerous as some of you are supposing it would not be available in over the counter type products.
Cheers
Steve (ex -chemist, and organic at that!)

Hi Steve
You are right that MEK alone is not a carcinogen however when mixed with acetone (like in some spray gun washes and other cleaners) it becomes a catalyst for the acetone and the combination is extemely carcinogenic. Australia had a Royal Commission on this about 20 years ago - you can find the report at www.aph.gov.au/Parliamentary_Business/Committees/House_of_representatives_Committees?url=jfadt/deseal_reseal/report/final report.pdf

 

[MiTasol]

About any paint in that era had lead in it, but only in the about 1% of content area.

Aircraft of the era used nitrocellulose lacquer as topcoat except on fabric which used butrate lacquer

 

[MiTasol]

[QUOTE="Aozora, post: 1063232, member: 51628"

[/QUOTE]
Hi Aozora (or is that Gidday)
It would appear from the above page that you have, or have access to, a copy of the P-51 manual 01-60JE-2
I have just obtained a copy that has been used as a childs scribble pad (fortunately with pencil so I can physically and digitally erase most of the damage with a little luck and a lot of work) but it is missing two sheets, pages 1/2 and 173/174.
If your manual is the same edition (and your copy and mine are probably the same because page 407 is identical tho mine is not watermarked) could you please copy these four pages and post them to the forum or PM them to me.
The attachment shows the manual I have. It is an earlier edition than the manual Avialogs have and those pages are much different in the Avialogs manual (which covers specific D and K models).
According to page A of my manual none of the missing pages were revised in Feb 45 so an original copy of the Dec 44 manual would have the same pages as I need.
Regards
Mi Tasol
.